An empirical distillation method analysis of the volatile matter content of coal and coke samples is intended to provide a measure of the volume of gaseous product, exclusive of the free moisture content, which is produced from such samples under a set of standard heating conditions. The volatile matter content is a parameter used in classifying coals and is significant in determining and designing compatible combustion hardware for use in the coal combustion process.
In the ASTM Standard Test Method for "Volatile Matter In The Analysis Sample of Coal and Coke", D 3175-73 (1973), a method is disclosed for determining the volatile matter content of coal or coke. The method involves weighing the coal sample, heating the coal sample to determine the weight loss after the heating, determining the moisture content of the coal sample using the standard found in ASTM D 3173, and then subtracting the moisture content from the weight loss. For the heating step, an operator determines, beforehand, the approximate desired position of the coal sample in a vertical tubular furnace by using a portable thermocouple. The thermocouple is not connected to the crucible but is, typically, a separate device inserted by the operator into the furnace for use in determining the temperature profile therein. In another known embodiment, a thermocouple device is connected to the furnace itself for providing an indication of the temperature thereof at that specific point in the furnace, usually the bottom, so that this may be used to adjust approximately the temperature of at least the hottest point of the temperature profile.
An automatic volatile analyzer of coke and coal is described in the EDP catalog with respect to the Preiser/Mineco volatile programmer. The analyzer described includes holding timers for use in determining when to move a crucible containing a coal sample to different positions in a furnace. Different descent rates of the crucible into the furnace area are also provided in this automatic analyzer. This analyzer moves the crucible as a function of time to preselected positions in the furnace. Although these preselected positions in the furnace are expected to be at desired temperatures, this is often not the case.